.tar is a linux compressed file like win's .zip.
To get the most recent php dist for windows go here...
http://us2.php.net/get/php-4.3.7-Win...from/a/mirror/
That is the binaries w/o the installer. I'm guessing your using Apache? If so do as follows to install php as an Apache module.
you can find Apache at
http://www.apache.org/ and you'll also need MySQL which you can find at
http://www.mysql.org/
As for the forum scripts Invission is good but i preffer phpBB which can be found at
http://www.phpbb.com It's just a matter of opinion both are good.
1. Download the PHP binary.zip
2. Unpack the php.zip To C:\
3. After doing that your php files will be @ C:\php-4.3.x or similar... rename C:\php-xxx to C;\PHP or C:\php
4. Open httpd.conf
file://C:\Program Files\Apache Group\Apache\conf\ for Apache 1.3.x or
file://C:\Program Files\Apache Group\Apache2\conf\ for Apache 2.0.x
5. In order for php to work with apache you must specify some thing in httpd.conf
For Apache 2.0.x
Add the lines...
LoadModule php4_module modules/libphp4.dll
AddType application/x-httpd-php php phtml
AddType application/x-httpd-php-source phps phtms
I think for Apache 1.3.x you need that above and AddHandler.
6. Open php.ini-recommended from C:\php\php.ini-recommended
save as C:\WINDOWS\php.ini
Copy libphp4.dll from C:\PHP to your Apache modules folder.
Copy php4apache2.dll from C:\php\sapi to you Apache root folder
7. Restart apache
8. Make test.php in your htdocs folder and insert the following...
[PHP]<?PHP phpinfo(); ?>[/PHP]
9. goto
http://127.0.0.1/test.php
If it worked you did it right.